Effects of bioaugmentation on enhanced reductive dechlorination of 1,1,1-trichloroethane in groundwater: a comparison of three sites

Microcosm studies investigated the effects of bioaugmentation with a mixed Dehalococcoides (Dhc)/Dehalobacter (Dhb) culture on biological enhanced reductive dechlorination for treatment of 1,1,1-trichloroethane (TCA) and chloroethenes in groundwater at three Danish sites. Microcosms were amended with lactate as electron donor and monitored over 600 days. Experimental variables included bioaugmentation, TCA concentration, and presence/absence of chloroethenes. Bioaugmented microcosms received a mixture of the Dhc culture KB-1 and Dhb culture ACT-3. To investigate effects of substrate concentration, microcosms were amended with various concentrations of chloroethanes (TCA or monochloroethane [CA]) and/or chloroethenes (tetrachloroethene [PCE], trichloroethene [TCE], or 1,1-dichloroethene [1,1-DCE]). Results showed that combined electron donor addition and bioaugmentation stimulated dechlorination of TCA and 1,1-dichloroethane (1,1-DCA) to CA, and dechlorination of PCE, TCE, 1,1-DCE and cDCE to ethane. Dechlorination of CA was not observed. Bioaugmentation improved the rate and extent of TCA and 1,1-DCA dechlorination at two sites, but did not accelerate dechlorination at a third site where geochemical conditions were reducing and Dhc and Dhb were indigenous. TCA at initial concentrations of 5 mg/L inhibited (i.e., slowed the rate of) TCA dechlorination, TCE dechlorination, donor fermentation, and methanogenesis. 1 mg/L TCA did not inhibit dechlorination of TCA, TCE or cDCE. Moreover, complete dechlorination of PCE to ethene was observed in the presence of 3.2 mg/L TCA. In contrast to some prior reports, these studies indicate that low part-per million levels of TCA (<3 mg/L) in aquifer systems do not inhibit dechlorination of PCE or TCE to ethene. In addition, the results show that co-bioaugmentation with Dhc and Dhb cultures can be an effective strategy for accelerating treatment of chloroethane/chloroethene mixtures in groundwater, with the exception that all currently known Dhc and Dhb cultures cannot treat CA.     

Characterization of microbial community structure and population dynamics of tetrachloroethene-dechlorinating tidal mudflat communities

Tetrachloroethene (PCE) and trichloroethene (TCE) are common groundwater contaminants that also impact tidal flats, especially near urban and industrial areas. However, very little is known about dechlorinating microbial communities in tidal flats. Titanium pyrosequencing, 16S rRNA gene clone libraries, and dechlorinator-targeted quantitative real-time PCR (qPCR) characterized reductive dechlorinating activities and populations in tidal flat sediments collected from South Korea’s central west coast near Kangwha. In microcosms established with surface sediments, PCE dechlorination to TCE began within 10 days and 100% of the initial amount of PCE was converted to TCE after 37 days. cis-1,2-Dichloroethene (cis-DCE) was observed as dechlorination end product in microcosms containing sediments collected from deeper zones (i.e., 35–40 cm below ground surface). Pyrosequencing of bacterial 16S rRNA genes and 16S rRNA gene-targeted qPCR results revealed Desulfuromonas michiganensis-like populations predominanted in both TCE and cis-DCE producing microcosms. Other abundant groups included Desulfuromonas thiophila and Pelobacter acidigallici-like populations in the surface sediment microcosms, and Desulfovibrio dechloracetivorans and Fusibacter paucivorans-like populations in the deeper sediment microcosms. Dehalococcoides spp. populations were not detected in these sediments before and after incubation with PCE. The results suggest that tidal flats harbor novel, salt-tolerant dechlorinating populations and that titanium pyrosequencing provides more detailed insight into community structure dynamics of the dechlorinating microcosms than conventional 16S rRNA gene sequencing or fingerprinting methods.     

Quantitative real-time PCR (qPCR) detection chemistries affect enumeration of the Dehalococcoides 16S rRNA gene in groundwater

Quantitative real-time PCR (qPCR) commonly uses the fluorogenic 5′ nuclease (TaqMan) and SYBR Green I (SG) detection chemistries to enumerate biomarker genes. Dehalococcoides (Dhc) are keystone bacteria for the detoxification of chlorinated ethenes, and the Dhc 16S ribosomal RNA (rRNA) gene serves as a biomarker for monitoring reductive dechlorination in contaminated aquifers. qPCR enumeration of Dhc biomarker genes using the TaqMan or SG approach with the same primer set yielded linear calibration curves over a seven orders of magnitude range with similar amplification efficiencies. The TaqMan assay discriminates specific from nonspecific amplification observed at low template concentrations with the SG assay, and had a 10-fold lower limit of detection of ~3 copies per assay. When applied to Dhc pure cultures and Dhc-containing consortia, both detection methods enumerated Dhc biomarker genes with differences not exceeding 3-fold. Greater variability was observed with groundwater samples, and the SG chemistry produced false-positive results or yielded up to 6-fold higher biomarker gene abundances compared to the TaqMan method. In most cases, the apparent error associated with SG detection resulted from quantification of nonspecific amplification products and was more pronounced with groundwater samples that had low biomarker concentrations or contained PCR inhibitors. Correction of the apparent error using post-amplification melting curve analysis produced 2 to 21-fold lower abundance estimates; however, gel electrophoretic analysis of amplicons demonstrated that melting curve analysis was insufficient to recognize all nonspecific amplification. Upon exclusion of nonspecific amplification products identified by combined melting curve and electrophoretic amplicon analyses, the SG method produced false-negative results compared to the TaqMan method. To achieve sensitive and accurate quantification of Dhc biomarker genes in environmental samples (e.g., groundwater) and avoid erroneous conclusions, the analysis should rely on TaqMan detection chemistry, unless additional analyses validate the results obtained with the SG approach.     

Sustainable remediation: electrochemically assisted microbial dechlorination of tetrachloroethene‐contaminated groundwater

Microbial electric systems (MESs) hold significant promise for the sustainable remediation of chlorinated solvents such as tetrachlorethene (perchloroethylene, PCE). Although the bio‐electrochemical potential of some specific bacterial species such as Dehalcoccoides and Geobacteraceae have been exploited, this ability in other undefined microorganisms has not been extensively assessed. Hence, the focus of this study was to investigate indigenous and potentially bio‐electrochemically active microorganisms in PCE‐contaminated groundwater. Lab‐scale MESs were fed with acetate and carbon electrode/PCE as electron donors and acceptors, respectively, under biostimulation (BS) and BS‐bioaugmentation (BS‐BA) regimes. Molecular analysis of the indigenous groundwater community identified mainly Spirochaetes, Firmicutes, Bacteroidetes, and γ and δ‐Proteobacteria. Environmental scanning electron photomicrographs of the anode surfaces showed extensive indigenous microbial colonization under both regimes. This colonization and BS resulted in 100% dechlorination in both treatments with complete dechlorination occurring 4 weeks earlier in BS‐BA samples and up to 11.5 μA of current being generated. The indigenous non‐Dehalococcoides community was found to contribute significantly to electron transfer with ～61% of the current generated due to their activities. This study therefore shows the potential of the indigenous non‐Dehalococcoides bacterial community in bio‐electrochemically reducing PCE that could prove to be a cost‐effective and sustainable bioremediation practice.     

Dechlorination of PCE by Mixed Methanogenic Cultures Using Hollow-Fiber Membranes

The study investigated the use of hollow-fiber membranes for hydrogen (H₂) delivery to support the biological reductive dechlorination of tetrachloroethene (PCE) Two experiments were performed in which H₂ was supplied through membranes placed in stirred batch reactors containing a mixed methanogenic/dechlorinating culture and PCE (≤10?µM. Reductive dechlorination of PCE to cis-dichloroethene was sustained in the reactors receiving H₂ (1% H₂ and 50% H₂), while negligible dechlorination was observed in control reactors (100% N₂). The 1%-H₂-fed reactor outperformed the 50%-H₂-fed reactor in the first experiment. However, the dechlorinating performance in the two reactors was similar in the second experiment. Despite relatively high H₂ concentrations (4.6 to 178?µM) that led to H₂ consumption (and CH₄ production) by methanogens, dechlorination was effectively maintained for the duration of the experiments (35 to 62 days). The results of this study are significant in that dechlorination was sustained in a minimal medium by membrane-delivered H₂. Dechlorination was also maintained at aqueous H₂ concentrations that exceeded the thermodynamic thresholds for not only dechlorination (<0.1 to 2?nM, but also methanogenesis (～10?n_M) and homoacetogenesis (94 to 400?n_M. The results of these experiments suggest that membranes are a promising H₂ delivery technology for stimulating the bioremediation of chlorinated ethene-contaminated aquifers.     

Mycorrhizal colonization decreases respiration of common bean nodulated root in hydroaeroponic culture

The bean-rhizobia symbiosis allows atmospheric nitrogen fixation through nodule formation. Nevertheless, nodule establishment in Mediterranean areas is subjected to various biotic and abiotic constraints such as phosphorus soils deficiency. This study compares plant-growth response to moderate (75 μmol KH₂PO₄ plant^?1 week^?1) versus severe phosphorus deficiency (30 μmol KH₂PO₄ plant^?1 week^?1) after inoculation with Rhizobium tropici CIAT 899 and Glomus intraradices of four Phaseolus vulgaris lines contrasting in P use efficiency (PUE) for their symbiotic nitrogen fixation (SNF) in hydroaeroponic culture. After 5 weeks of growth under glasshouse conditions, the oxygen consumption related to nitrogen fixation was measured on intact nodulated roots. The obtained results revealed that mycorrhizal colonization decreased the nodulated-roots O₂ consumption of P. vulgaris under both P deficiencies although it increased the growth of all plant organs and the nodulation with a large genotypic variability. Moreover, mycorrhizal colonization was higher under severe P deficiency than under moderate one. In conclusion, the tripartite inoculation improved growth parameters under severe P-deficiency with a decrease in nodulated root O₂ consumption.     

Phanerochaete chrysosporium inoculation shapes the indigenous fungal communities during agricultural waste composting

Inoculation with exogenous white-rot fungi has been proven to be an efficient method to promote lignocellulose biodegradation during agricultural waste composting. Indigenous fungal communities, the most important organisms responsible for mineralization and decomposition of lignocellulosic materials in composts, can be affected by sample properties and other biotic factors. This research was conducted to determine the effects of the Phanerochaete chrysosporium inoculation on the indigenous fungal communities during agricultural waste composting. Fungal communities in samples with different inoculation regimes were investigated by sequencing and quantitative PCR. Results showed that P. chrysosporium inoculants produced significant negative effects on the indigenous fungal community abundance during the thermophilic stage. Samples inoculated during Phase II contained higher proportion of Acremonium chrysogenum and Galactomyces geotrichum, while those non-inoculated samples were dominated by Coprinopsis cinerea and Scytalidium thermophilum. Moreover, the indigenous fungal community abundance was significantly correlated with the C/N ratio, water soluble carbon and moisture content (P < 0.05). Redundancy analysis indicated that the most variation in distribution of indigenous fungal community structure was statistically explained by nitrate, C/N ratio, and moisture content, factors which solely explained 29.6 % (F = 30.316, P = 0.002), 25.6 % (F = 26.191, P = 0.002) and 10.0 % (F = 10.249, P = 0.002) of the variation in the indigenous fungal community structure, respectively.     

Global warming effects on benthic macroinvertebrates: a model case study from a small geothermal stream

The aim of this study was to predict global warming effects on benthic macroinvertebrate community structure by using a small temperate geothermal stream as a model system. We collected benthic macroinvertebrates, measured physical and chemical water properties at eight localities up the Kudo?ki stream steep water temperature gradient, and used 11 metrics and indexes to characterize community structure. Species richness and evenness decreased, but total abundance increased with the increase of average annual water temperature (t _av), with species richness being most and total abundance least sensitive to this parameter. The increase of Gastropoda relative abundance and the decrease of Ephemeroptera, Plecoptera and Trichoptera richness, respectively, were the earliest responses of taxonomic groups to t _av increase. Relative abundance of Orthocladiinae decreased and that of Chironomini increased with the increase of t _av. This indicates that Chironomidae are not reliable predictors of global warming effects in running waters, and that lower taxonomic levels, subfamily or tribe, are more suitable for that purpose. Changes in community structure did not linearly follow t _av increase, since a great community shift was observed at t _av ≈ 20°C indicating that present trends of community responses to changes in climatic conditions should not be linearly extrapolated to future warming.     

Temperature-dependent development of the broad mite Polyphagotarsonemus latus (Acari: Tarsonemidae) on Rhododendron simsii

The broad mite, Polyphagotarsonemus latus (Banks), is one of the major pests causing severe economic damage in Rhododendron simsii Planch hybrid production in Belgium. In order to optimize biological control programs and to parameterize warning programs, we studied the effect of environmental temperature on the development of P. latus on R. simsii leaves. In combination with a photoperiod of 16:8 h (L:D) and a relative humidity of 80 ± 5 %, six constant temperatures (15, 17, 20, 25, 30 and 33 ± 1 °C), were studied. Total developmental times of 13.3, 10.5, 6.6, 4.2, 3.5 and 4.0 days were measured, respective to each of the aforementioned temperatures. Development of females took significantly longer than that of males at 15, 17, 20 and 30 °C. Survival rates observed between 17 and 30 °C varied between 43.5 and 96.9 %. Lower survival rates were found at 15 and 33 °C, i.e. 31.8 and 23.6 %, respectively. The lower, optimal and upper developmental threshold (t _min , t _opt and t _max , respectively) and thermal constant (K) of the pest were estimated for each life stage by a linear and two non-linear models. Based on measurements of total development of P. latus thermal thresholds of 10.0, 30.1 and 36.0 °C were calculated for t _min , t _opt and t _max , respectively. The number of degree-days needed to complete immature development when feeding on R. simsii was 66.7.     

Predicting Treatment Response of Breast Cancer to Neoadjuvant Chemotherapy Using Ultrasound-Guided Diffuse Optical Tomography

PURPOSE: To prospectively investigate ultrasound-guided diffuse optical tomography (US-guided DOT) in predicting breast cancer response to neoadjuvant chemotherapy (NAC). MATERIALS AND METHODS: Eighty-eight breast cancer patients, with a total of 93 lesions, were included in our study. Pre– and post–last chemotherapy, size and total hemoglobin concentration (THC) of each lesion were measured by conventional US and US-guided DOT 1 day before biopsy (time point t0, THC THC0, SIZE S0) and 1 to 2 days before surgery (time point tL, THCL, SL). The relative changes in THC and SIZE of lesions after the first and last NAC cycles were considered as the variables ΔTHC and ΔSIZE. Receiver operating characteristic curve was performed to calculate ΔTHC and ΔSIZE cutoff values to evaluate pathologic response of 93 breast cancers to NAC, which were then prospectively used to predicate response of 61 breast cancers to NAC. RESULTS: The cutoff values of ΔTHC and ΔSIZE for evaluation of breast cancers NAC treatment response were 23.9% and 42.6%. At ΔTHC 23.9%, the predicted treatment response in 61 breast lesions for the time points t1 to t3 was calculated by area under the curve (AUC), which were AUC₁ 0.534 (P = .6668), AUC₂ 0.604 (P = .1893), and AUC₃ 0.674(P =. 0.027), respectively; for ΔSIZE 42.6%, at time points t1 to t3, AUC₁ 0.505 (P = .9121), AUC₂ 0.645 (P = .0115), and AUC₃ 0.719 (P = .0018). CONCLUSION: US-guided DOT ΔTHC 23.9% and US ΔSIZE 42.6% can be used for the response evaluation and earlier prediction of the pathological response after three rounds of chemotherapy.     

Determination of delay time in individual transfer function for central aortic pressure reconstruction

In previous research,time-delay(Δt)was a more important parameter than the reflection coefficient in the individual transfer function of central aortic pressure reconstruction.TheΔt can be obtained by electrocardiography(ECG)or phonocardiography(PCG).Because the pre-ejection period remains an uncertain factor,the present study used ECG and PCG to define the delay time and analyzed the accuracy of the reconstruction results.TheΔtpre is the actual delay time derived from the aorta to the carotid pressure wave,ΔtPCG is the time delay between the aortic valve component of the second heart sound and the dicrotic incisura of the carotid pressure wave,andΔtECG represents the delay from the interval of the ECG R-peak to the foot of the carotid pressure wave.Compared with the measured aortic pressure,the reconstruction result obtained byΔt=ΔtPCG slightly differed from the best result estimated byΔt=Δtpre.However,the differences between the result obtained byΔt=ΔtECG and the best result were significant in terms of the diastolic blood pressure,and pulse pressure,and especially in terms of the augmentation index and root-mean-square-error.Thus,theΔt should be determined by PCG for central aortic pressure reconstruction in practice.     

DFT and docking studies of rhodostreptomycins A and B and their interactions with solvated/nonsolvated Mg2+ and Ca2+ ions

The interactions of L-aminoglucosidic stereoisomers such as rhodostreptomycins A (Rho A) and B (Rho B) with cations (Mg²⁺, Ca²⁺, and H⁺) were studied by a quantum mechanical method that utilized DFT with B3LYP/6-311G**. Docking studies were also carried out in order to explore the surface recognition properties of L-aminoglucoside with respect to Mg²⁺ and Ca²⁺ ions under solvated and nonsolvated conditions. Although both of the stereoisomers possess similar physicochemical/antibiotic properties against Helicobacter pylori, the thermochemical values for these complexes showed that its high affinity for Mg²⁺ cations caused the hydration of Rho B. According to the results of the calculations, for Rho A–Ca²⁺(H₂O)₆, ΔH = ?72.21 kcal?mol^?1; for Rho B–Ca²⁺(H₂O)₆, ΔH = ?72.53 kcal?mol^?1; for Rho A–Mg²⁺(H₂O)₆, ΔH = ?72.99  kcal?mol^?1 and for Rho B–Mg²⁺(H₂O)₆, ΔH = ?95.00  kcal?mol^?1, confirming that Rho B binds most strongly with hydrated Mg²⁺, considering the energy associated with this binding process. This result suggests that Rho B forms a more stable complex than its isomer does with magnesium ion. Docking results show that both of these rhodostreptomycin molecules bind to solvated Ca²⁺ or Mg²⁺ through hydrogen bonding. Finally, Rho B is more stable than Rho A when protonation occurs.

Two-Probe Microfluorometry Estimation of Transmembrane Potential (ΔΨ p) Slight Changes in Individual Hepatocytes Under Short-Term Hormone Action

Early events in individual hepatocytes of rat activated by adrenaline (10^?6M) and phenylephrine (10^?5M) have been investigated by quantitative image microfluorometry and microspectrofluorometry. Cationic DiOC₂ and anionic SqSC₄ probes have been used for image analysis and transmembrane potential (ΔΨ _p) estimation in real-time studies. Fluorescence spectra resulting from the accumulation of dyes in single cells were recorded. Based on the mean fluorescence intensity, the magnitude of ΔΨ _p was calculated by Nernst equation adapted for lipophilic cationic probes. DiOC₂ has revealed that both hormones induce biphasic hyperpolarization of hepatocytes membrane with α-agonist phenylephrine causing ΔΨ _p changes at higher amplitude. The first increase of ΔΨ _p within 2 and 5 min (ΔΔΨ _p = ?8.6 ± 4.2 mV) apparently related to Na⁺/K⁺-ATPase activation by the Ca²⁺-mobilizing hormone. The second peak of hyperpolarization (ΔΔΨ _p = ?13.2 ± 3.2 mV) between 25 and 30 min, after a transient decrease of ΔΨ _p (ΔΔΨ _p = 10.9 ± 4.3 mV) over 15 min experiment, probably is mediated by phenylephrine stimulating action on K⁺-channels. K⁺ channel blocker (Ba²⁺ or 4-aminopyridine) as well as elevating of extracellular K⁺ prevented the hyperpolarization. Modulation of PLD-dependent signal transduction pathway by 0.4 % butanol had a weak influence on the first increase of ΔΨ _p but it abolished the second phase of hyperpolarization. That points to PLD involvement in the ΔΨ _p fluctuations mediated by K⁺-channels in response to phenylephrine. Based on SqSC₄, fluorescent parameters estimation of relative changes of ΔΨ _p revealed similar character of time dependence with two phases of hyperpolarization. Synchronic fluctuation of ΔΨ _p determined by oppositely charged probes demonstrate that the quantitative microfluorometry allows to evaluate slight ΔΨ _p changes separately from ΔΨ _m in non-excitable individual cells at the short-term hormone action.     

Biochemical and molecular characterization of a tetrachloroethene dechlorinating Desulfitobacterium sp. strain Y51: a review

A strict anaerobic bacterium, Desulfitobacterium sp. strain Y51, is capable of very efficiently dechlorinating tetrachloroethene (PCE) via trichloroethene (TCE) to cis-1,2-dichloroethene (cis-DCE) at concentrations as high as 960 μM and as low as 0.06 μM. Dechlorination was highly susceptible to air oxidation and to potential alternative electron acceptors, such as nitrite, nitrate or sulfite. The PCE reductive dehalogenase (encoded by the pceA gene and abbreviated as PceA dehalogenase) of strain Y51 was purified and characterized. The purified enzyme catalyzed the reductive dechlorination of PCE to cis-DCE at a specific activity of 113.6 nmol min⁻¹  mg protein⁻¹ . The apparent K _m values for PCE and TCE were 105.7 and 535.3 μM, respectively. In addition to PCE and TCE, the enzyme exhibited dechlorination activity for various chlorinated ethanes such as hexachloroethane, pentachloroethane, 1,1,1,2-tetrachloroethane and 1,1,2,2-tetrachloroethane. An 8.4-kb DNA fragment cloned from the Y51 genome revealed eight open reading frames, including the pceAB genes. Immunoblot analysis revealed that PceA dehalogenase is localized in the periplasm of Y51 cells. Production of PceA dehalogenase was induced upon addition of TCE. Significant growth inhibition of strain Y51 was observed in the presence of cis-DCE, More interestingly, the pce gene cluster was deleted with high frequency when the cells were grown with cis-DCE.

     

Design,synthesis, biological evaluation and molecular modelling studies of novel diaryl substituted pyrazolyl thiazolidinediones as potent pancreatic lipase inhibitors

A series of novel diaryl substituted pyrazolyl 2,4-thiazolidinediones were synthesized via reaction of appropriate pyrazolecarboxaldehydes with 2,4-thiazolidinedione (TZD) and nitrobenzyl substituted 2,4-thiazolidinedione. The resulting compounds were screened in vitro for pancreatic lipase (PL) inhibitory activity. Two assay protocols were performed viz., methods A and B using p-nitrophenyl butyrate and tributyrin as substrates, respectively. Compound 11e exhibited potent PL inhibitory activity (IC₅₀ = 4.81 µM and X_i50 = 10.01, respectively in method A and B), comparable to that of the standard drug, orlistat (IC₅₀ = 0.99 µM and X_i50 = 3.72). Presence of nitrobenzyl group at N-3 position of TZD and nature of substituent at para position of phenyl ring at C-3 position of pyrazole ring notably affected the PL inhibitory activity of the tested compounds. Enzyme inhibition kinetics of 11e revealed its reversible competitive inhibition, similar to that of orlistat. Molecular docking studies validated the rationale of pharmacophoric design and are in accordance to the in vitro results. Compound 11e exhibited a potential MolDock score of ?153.349 kcal/mol. Further, the diaryl pyrazolyl wing exhibited hydrophobic interactions with the amino acids of the hydrophobic lid domain. Moreover, the carbonyl group at 2^nd position of the TZD ring existed adjacent to Ser 152 (≈3 Å) similar to that of orlistat. A 10 ns molecular dynamics simulation of 11e–PL complex revealed a stable binding conformation of 11e in the active site of PL (Maximum RMSD ≈ 3 Å). The present study identified novel thiazolidinedione based leads with promising PL inhibitory activity. Further development of the leads might result in potent PL inhibitors.     

Analysis of formulae for determination of seaweed growth rate

The increasing demand for products derived from seaweeds has led to an increasing amount of research being directed towards studies related to their growth and productivity. Several investigators have attempted to develop different formulae for the estimation of growth rates and caused confusion to the readers. In this study, accuracy and reliability of the average growth rate formulae were analyzed using geometric progression theory and compared to each other. The lowest degree of error (0.023 %) and the highest matched point (61.90 %) was achieved by applying [(W _t ?/?W ₀)^1/t ???1]?×?100 % in growth rate determination. This formula has been tested and proven to be the most accurate among all the currently available ones.     

A novel series of C<Subscript>18</Subscript>–C<Subscript>22</Subscript><Emphasis Type="Italic">trans</Emphasis> ω3 PUFA from Northern and Southern Hemisphere strains of the marine haptophyte <Emphasis Type="Italic">Imantonia rotunda</Emphasis>

A series of novel C₁₈–C₂₂ trans ω3 polyunsaturated fatty acids (PUFA) with a single trans double bond in the ω3 position was found in Northern and Southern Hemisphere strains of the marine haptophyte Imantonia rotunda. The novel ω3 PUFA were identified as 18:3(9c,12c,15t) (0.2–1.8 % of total fatty acids), 18:4(6c,9c,12c,15t) (1.9–4.1 %), 18:5 (3c,6c,9c,12c,15t) (0.7–8.8 %), 20:5(5c,8c,11c,14c,17t) (1.2–4.1 %) and 22:6(4c,7c,10c,13c,16c,19t) (0.3–4.3 %), and were accompanied by larger proportions of the all cis isomers: 18:3ω3(9,12,15) (2.7–3.5 %), 18:4ω3(6,9,12,15) (9.3–14.3 %), 18:5ω3(3,6,9,12,15) (7.8–18.5 %), 20:5ω3(5,8,11,14,17) (3.2–3.9 %), 22:5ω3(7,10,13,16,19) (0.1–0.3 %) and 22:6ω3(4,7,10,13,16,19) (2.3–5.2 %). GC analysis of FAME using a non-polar column did not reveal the trans isomers as they coeluted with the all cis PUFA. However, GC using a polar column resolved the trans PUFA from the all cis PUFA, with the trans isomers eluting before the all cis isomers. GC-MS of FAME fractionated by argentation solid-phase chromatography confirmed the molecular ions of all components. FAME were derivatized to form 4,4-dimethyloxazoline (DMOX) derivatives, and GC-MS revealed the same double bond positions for each trans and cis FAME. The results suggest that the ω3 trans double bond originated from the Δ15/ω3 desaturation of 18:2(9c,12c), suggesting that this desaturase has dual cis/trans activity in these species. These results indicate that 18:3(9c,12c,15?t) was the precursor trans isomer produced for the trans series and further desaturation by the common Δ6 desaturase to produce the trans tetraene and successive elongations and desaturations led to the subsequent series of trans ω3 PUFA isomers. To our knowledge, this is the first report of these trans ω3 isomers occurring in strains of I. rotunda. These trans ω3 PUFA may be used as biomarkers in marine food webs for this species and with their unique structure may be biologically active.     

Spectral Characteristics of Near-Infrared Surface Plasmon Resonance

Intrinsic properties of surface plasmons (SPs) excited with Kretschmann configuration were analyzed as a function of wavelength, including the propagation length, the penetration depth, the Goos–Hänchen (GH) shift, and the field enhancement. The calculated results indicate that there exists a critical thickness (t _cr) of the gold layer and that the maximum GH shift occurring exactly at the SP resonance wavelength (λ _R) rapidly varies from positive to negative with changing of the gold layer thickness from t?<?t _cr to t?>?t _cr. The maximum field enhancement happens not at λ _R but at a wavelength smaller than λ _R due to the phase retardation between the transmitted and reflected light. Simulations also reveal that a broadband collimated near-infrared beam can simultaneously excite two SPs with different responses to a refractive index (RI) change: the shorter-wavelength SP able to make a small redshift and the longer-wavelength SP capable of yielding a large blueshift. Only the shorter-wavelength SP was experimentally observed and its RI sensitivity was measured to increase from 3,539 nm/RIU at λ _R?=?707.6 nm to 57,143 nm/RIU at λ _R?=?1,398 nm. The SP at λ _R?=?1,013 nm moved to λ _R?=?1,029 nm in response to the saturation adsorption of bovine serum albumin, and the corresponding surface coverage was determined to be Γ?=?1.565 ng/mm² based on a quasilinear dependence of Γ on the resonance wavelength shift (?λ _R) deduced theoretically. Butyrylcholinesterase adsorption from a dilute solution of 10 nM protein in phosphate buffer solution leads to a redshift of ?λ _R?=?10 nm, corresponding to Γ?≈?0.97 ng/mm².